The mayor of a remote Sunni town in western Iraq that is under the control of Islamic State (IS) militants says about 200 residents who were part of a rare protest against the militant group have been detained at an unknown location.

Imad al-Rishawy, the mayor of the town of Rutbah in Anbar Province near the border with Jordan, says residents are gripped by fears that the 200 detainees will be killed by the IS fighters.

Rishawy said the trouble in Rutbah began on August 29 when IS militants killed a local resident who had killed an IS fighter as part of a long-running tribal blood feud.

Hundreds of residents protested later on August 29 against the killing and clashes broke out with the militants who tried to disperse the demonstrators.

A provincial official in Anbar said more than 100 of the demonstrators were tied to lampposts in Rutbah for about 24 hours as a punishment while others were detained and taken away.